1. Field of the Invention
The present invention relates to a fieldbus interface board that can improve communication efficiency.
2. Description of the Related Art
Currently, fieldbus interface technology is developed to enable interfacing of digital serial communication controlling control devices, sensors, actuators, etc., in a field of control in factory automation.
FIG. 1 is a block diagram showing a conventional fieldbus interface board. Referring to FIG. 1, the conventional fieldbus interface board includes a microcontroller 1 having a ROM 1a to store an information exchange program and input/output ports. The microcontroller 1 outputs an address to store information and an address latch enable signal ALE. The interface board further includes latches 2 and 2a to separate a lower byte address LOW ADDR and a higher byte address HIGH ADDR inputted to the microcontroller 1, in response to the address latch enable signal ALE, and to maintain the separated addresses for a certain period of time. A first decoder 5 deciphers the addresses LOW ADDR and HIGH ADDR from the latches 2 and 2a and outputs a chip selection signal CS to a chip selection terminal of a system RAM 3 or a dual port RAM 4. A bi-directional first bus transceiver 6 transmits lower byte data LOW DATA inputted to the microcontroller 1 to the system RAM 3 and the dual port RAM 4. A bi-directional second bus transceiver 6a transmits higher byte data HIGH DATA inputted to the microcontroller 1 to the system RAM 3 and the dual port RAM 4. A Manchester encoder/decoder 9 is provided to Manchester-encode data inputted and decode Manchester-encoded data, and first and second latch/shift registers 7 and 8 are provided, each connected to the system RAM 3, the dual port RAM 4, and the Manchester encoder/decoder 9. An interface 10 interfaces data exchanged between the Manchester encoder/decoder 9 and a fieldbus (not shown). A Cyclic Redundancy Checking (CRC) device 11 checks data errors, and a personal computer interface 12 exchanges data with a computer (not shown).
The conventional fieldbus interface board functions to control an operation of the interface board and fieldbus communication through the microcontroller 1. Accordingly, the microcontroller 1 controls both the operation of the interface board and fieldbus communication at the same time, so the construction of the interface board is complicated and a processing speed of the interface board is reduced owing to an amount of data to be processed.
Additionally, the conventional fieldbus interface board is problematic in that different types of data being inputted and outputted are not distinguished from one another, thereby causing difficulty with high-speed control.